Door and brake interlock device



Feb. 23, 1937. E. E. HEWITT I DOOR AND BRAKE INTERLOCK DEVICE Fi-led Nov. 16, 1933 k9 INVENTOR ELLIS E.HEWITT ATTORNEY Patented Feb. 23, 1937 PATENT OFFICE DOOR AND BRAKE INTERLOOK DEVICE Ellis E. Hewitt, Edgewood, Pa, assignor to The Westinghouse Air Brake Company, Pin, a corporation of Pennsylvania Wilmerding,

Application November 16, 1933, Serial No. 698,231

22 Claims.

This invention relates to control apparatus for fluid pressure actuated equipment and particularly to control apparatus for controlling the fluid pressure actuated brakes, door engine and appurtenant devices of motor driven passenger vehicles such as transit coaches and motor coaches.

In the copending application of David W. Lloyd, Serial No. 698,242, filed November 16, 1933, assigned to the assignee of this application, control apparatus for a passenger vehicle is disclosed, wherein an improved brake valve device is associated with a treadle door engine device, an improved manually operable controlling device for said brake valve device and said door engine device, and a current actuated valve device for controlling the operation of the treadle door engine device and which is controlled by a foot operated treadle disposed in front of the exit or treadle door and upon which an outgoing passenger treads when leaving the car.

An object of this invention is to provide control apparatus, such as disclosed in the above noted copending application, with means interlocking the control mechanism for the door engine device with the brake valve device for insuring retention of the brake valve device in brake applied position so long as the treadle door is open and the passenger is standing upon the current controlling treadle device, and for effecting an application of the brakes sufiicient to bring the vehicle to rest in the event that the brake valve device has not, previous to the effecting of opening of the treadle door, been moved sufficiently to 'eiiect a service application of the brakes.

A further object of the invention is to provide an interlocking device of the character above described, that-is adjustable so that any desired degree of brake application may be assured by said device.

1 A further object of the invention is to provide control mechanism of the above describedcharacter, wherein the door or door engine device is so interlocked with the brake switch device and interlocking piston that the brake switch device 7 may not be returned to release position without first effecting closing movement of the door, and so that the door engine device will remain in door open position so long as the treadle in front of the door is depressed as by a passenger treading or standing upon it.

These and other objects of the invention that will be made apparent throughout the further description thereof are attained by means of the apparatus hereinafter described and illustrated in the accompanying drawing.

The figure is a diagrammatic elevational view, partly in section, of the safety car control equipment embodying features of the invention.

Referring tothe drawing, the control equipment comprises a brake cylinder l I, a main reservoir [2, a brake valve device l3 for controlling the supply of fluid from the main reservoir to the brake cylinder, a manually operated control device 14, a door engine device l5 for actuating the vehicle door, a magnet valve device l6 for controlling the operation of the door engine device, a pilot switch device I! for controlling the supply of current to the magnet valve device, a treadle switch device 18 for also controlling the current supplied to the magnet valve device and an interlock piston device I9.

The brake valve device I3 is of the type disclosed in the above mentioned copending application and is provided with an operating lever 2! that is movable from the release position shown in the drawing to full application position indicated by the dotted line, wherein the valve parts of the brake valve device are in application position for supplying fluid from the main reser voir l2 to the brake cylinder l I. A spring 22 that is attached at one end to the lever 2| and at the other end to a clip 23 supported upon the casing 24, serves to normally yieldingly retain the brake valve device in release position against an adjustable stop screw 25 mounted on the casing 24.

The manually operated controlling device [4 comprises a casing 26 having a chamber 21 that is open to the atmosphere through a passage 28 and which contains a rotatable shaft 29 that extends exteriorly of the casing and which is provided with 'a hand operating handle 3| by means of which the shaft 29 may be rotatively oscillated. The shaft is provided with two cam members 32 and 33, the former serving to actuate a lever 34 that is pivotally mounted within the chamber 21 upon a pin 35, the lever 34 being adapted to engage and operate a pin 36 slidably mounted for vertical movement in the casing 26. The ends of the pin 36 extend from the casing and the upper end is provided with a button 31 that is adapted to be engaged by a foot operated lever 33 that is pivotally connected to the casing 26 by means of a pin 39. The lower end of the pin 36 engages an arm 4| of a bell-crank lever 42 that is pivotally connected to the floor 43 of the vehicle by means of a pin 44. The free end of the bellcrank lever 42 is pivotally connected to the operating lever 2| of the brake valve device by means of an adjustable rod 45. When the pin 36 is depressed either by downward movement of the foot operated pedal 38 or by rotary movement of the shaft 29 through the medium of the cam 32 and the lever 34, the operating arm 2| of the brake valve device is turned in a clockwise direction toward application position.

Casing 26 of the manually operated controlling device I4 also has a chamber 46 containing a Valve 41 that is yieldingly held seated upon a valve seat 48 by means of a spring 49. The valve 41 is provided with a fluted stem 5| which extends into a chamber 52, intermediate the chambers 21 and 46, which is connected to a passage and pipe 53 leading to a fluid pressure actuated switch device IT, to be hereinafter described.

Within the chamber 2'! is a valve 54 that is adapted to be moved into seating position upon a seat 55 by means of the cam 33 that engages a stem 56 on the valve 54. The valve 54 is provided with a fluted stem 51 which extends through a bore 58 into the chamber 52 and engages the end of the stem 5|, so that when the valve 54 is seated by reason of movement of the cam 33 engaging the stem 56, the valve 41 is unseated against the action of the spring 49, so that fluid under pressure may flow from the main reservoir I2 to the chamber 59 of the switch device I1, in a manner to be hereinafter described.

The pilot switch device I? comprises acasing 58 having a chamber 59 containing a valve piston 6| that is normally yieldingly retained in upper or switch open position by means of a spring 62. The piston BI is provided with a stem 63 carrying a bridging contact member 64 that is electrically insulated from the stem 63 by means of insulating material 65. The bridging switch member 64 is adapted. when in lower switch closed position to engage contacts 66 and conductively connect the conductors 6! and 68 of the electrical interlock control circuit, the former conductor being connected to the trolley wire or conductor 69 by means of the usual power take-off wheel II.

The treadle door engine device I5 for operating the car door 69 comprises a casing having oppositely disposed piston chambers 12 and I3 containing pistons I4 and 15, respectively, and a central chamber 16 containing a gear segment 11 fixed to a rotatable shaft 16, which is connected to the door mechanism by means of a rod 59. The pistons I4 and I5 are connected by rod 36 constituting a gear rack having teeth which mesh with those of the gear segment 11 and which rotates the gear segment as the pistons move to their operative positions, the pistons being in the closed door position as shown in the figure. Also within the casing II is a piston chamber l9 containing a piston 8| and a Valve chamber 82 containing a slide valve 83 that is adapted to be operated by a piston stem 84 connected to the piston 9|. The piston BI is biased toward the left position by a spring 85 disposed between the piston and the closure 86. The valve chamber 82 is normally open to the 'main reservoir i2 through pipe and passage 81 and pipe 49, and the fluid under pressure within the valve chamber 82 normally holds the piston 8| in its right position against the action of the spring 85, in which position the cavity 88 in the slide valve 83 connects the passage 89 in the casing II to atmospheric passage 9|. Passage 89 opens into the piston chamber I3 and with the piston 8| in door closed position shown, fluid is vented from the piston chamber 33 to the atmosphere.

When fluid imder pressure is supplied from the main reservoir I2 to the piston chamber I9 through the operation of a magnet valve device I6 to be hereinafter described, the piston 8| is moved to the left position, wherein the passage 99 is connected through the cavity 88 of the slide valve 83 to the atmospheric passage 9|.

With the valve 83 in the left position or door open position, fluid under pressure flows from the valve chamber 82 to the piston chamber I3 through passage 89 and the fluid under pressure acting on the face of the piston I5 forces the piston to the left or door open position, so that the gear segment "I"! is rotated in a clockwise direction and causes opening movement of the door rod 50, to the position shown in dotted lines in the drawing.

The magnet valve device I6 comprises a casing 92 having valve chambers 93 and 94 containing valves 95 and 96 respectively, and in electromagnet winding 91 for operating a core member 98 which constitutes a stem for the valve 96. The valve 96 is provided with a fluted stem 99 that is guided in a bore which opens into a central chamber I02 which is open to passage and pipe I99. The valve chamber 94 is open to the atmosphere through an atmospheric passage I63. The valve 95 is provided with a fluted stem I04 which is guided in a bore I95 in the casing 92 which communicates with the central chamber I92. A spring I06 contained in the valve chamber 93 engages the end of the valve 95 and normally retains it in seated position as shown, when the magnet winding 97 is deenergized. Fluid under pressure is supplied to the valve chamber 93 from the main reservoir through pipe 49 and pipe and passage 81.

The treadle switch device I8 comprises a bridging switch member III which serves to electrically connect conductors 68 and N2, the latter being connected to a terminal of the winding 91 of the electro-magnet valve device. The other terminal of the winding 91 is connected to ground or to the car frame. The pilot switch device I1 and switch device I8 are connected in series, so that when both the switch members 64 and II I thereof are in engagement with their respective contacts 66 and H3, current flows from the power conductor 69 to the ground through the magnet winding 91 of the electrical magnet device and causes the valve 96 to be seated and the valve 95 to be unseated.

The interlocking piston device I9 comprises a casing ||4 having a piston chamber 5 containing a piston II6 having a stem II 1 provided with a bore I I8 in which a rod I I9 is mounted for limited universal movement. The rod I I9 is threaded for receiving a threaded clevis I2I, which is pivotally connected to the operating lever 2| by means of a pin I 22. A locking nut I23 is threaded upon the rod II 9 for looking the clevis I2| in adjusted position on the rod II 9, so that the length thereof may be varied in order to vary the length of the stroke of the piston I I 6. The piston I I6 is normally biased toward its left position shown in the figure, by the spring 22 through the medium of the operating lever 2| and the rod H9. The piston chamber II 5 is connected to the pipe I so that it may be supplied with fluid under pressure from the main reservoir I2 when the valve is open and in a manner to be hereinafter described. When fluid under pressure is supplied to the piston chamber II5, the fluid acting upon the left face of the piston II6 forces it to the right and moves the operating lever 2| in a clockwise direction to effect movement of the brake valve device to an application position, which position is determined by the length of the rod H9 and the associated clevis I2I and the distance between the shoulder I20 on the piston I I6 and the threaded bushing I30 that is threaded. into the casing I.

In operation, assuming the parts of the apparatus to be in release position, wherein the brakes are released and the vehicle door is in closed position, and that the vehicle is running and it is desired to effect an application of the brakes, the operator depresses the foot pedal 38 and thereupon depresses the operating pin 36 and turns the bell-crank lever 52 in a counter-clockwise direction for effecting movement of the operating lever H of the brake valve device I3 to application position. The brake valve device is of the self-lapping type, such as disclosed in the above noted copending application, and the degree of brake application effected is substantially proportional to the degree of movement of the operating lever 2I toward full application position. The specific construction of the self-lapping device forms no part of the invention and the details of construction thereof are not herein specified, but it will here be understood that when the operating lever 2| is moved into engagement with the stop lug I24, fluid at main reservoir pressure is supplied to the brake cylinder and that when the operating lever 2| is at points intermediate the stop screw 25 and the stop lug I24, fluid under pressure at less than main reservoir pressure is supplied to the brake cylinder, the pressure of the fluid actually supplied to the brake cylinder being dependent upon the position of the operating lever 2 I. When the desired application of the brakes has been effected, the operator retains the foot pedal 38 .in the depressed condition so as to retain the vehicle at rest after it has been brought to a stop.

When the car has stopped, the operating handle 3| is rotated so that the cam 33 seats the valve 54 and unseats the valve 41 for effecting closure of the pilot switch device I1. With the valve 54 seated and the valve 41 unseated, the chamber 52 is closed to the atmosphere and fluid under pressure then flows from the main reservoir I2 to the piston chamber 59 of the pilot switch device I1 through pipe 40, chamber 46, past the open valve 41, chamber 52, and passage and pipe 53. The fluid under pressure acting on the upper face of the piston 6| forces it downwardly, thereby moving the bridging switch member 64 into engagement with the contact 56. Closing of the pilot switch I1, however, does not effect energization of the electro-magnet valve device because the treadle switch device I8 is open. When a passenger intending to leave the vehicle treads or stands upon the treadle device I8, the bridging switch member II I is depressed and moved into engagement with the contact H3, thereupon closing the circuit through the magnet winding. 91 from the feed conductor 69 to the ground through take-off wheel 10, conductor 61, contact 66, bridging switch member 64, contact 66, conductor 68, contact II3, bridging switch member III, contact II3, conductor II2, magnet winding 91 and ground connection I25.

Energization of the magnet winding 91 of the electro-magnet valve device It seats the valve 96 and unseats the valve 95 against the action of the spring I06. With the valve 96 seated and the valve 95 uns'eated, fluid under pressure flows from the main reservoir I2 to the piston chamber .19 of thedoor engine device I5 through pipe 40, pipe 81, chamber 93, past the open valve 95, chamber I02, and passage and pipe I00. Fluid under pressure at main reservoir pressure plus the tension of spring acting on the right face of the piston 8| overcomes the fluid under pressure at main reservoir pressure acting on the left face of the piston and forces the piston to the left, carrying with it the slide valve 83, so that passage 89 is uncovered by the slide valve and the passage 90 is connected to the atmospheric passage 9i through the cavity 88 in the slide valve 83. The chamber 12 is thus opened tothe atmosphere through passage 90, cavity 88, and the atmospheric port SI, and the higher fluid pressure acting on the right face of the piston 15 forces the piston 15 and rack rod 80 to the left causing the gear segment 11 to be rotated in a counter-clockwise direction, so that the door 69 is moved to the open position shown in dotted lines in the figure. The door 60 carries a bridging switch member I25 which engages contacts I21 when the door is in the open position, thus establishing a circuit through conductors i28 and I29, which shunts the pilot switch I1 so that the circuit through the electro-magnet winding 91 will be maintained even though the bridging switch 52 is returned to open position as the door controlling handleti is moved to release or door open position. This construction provides for maintaining fluid pressure on the piston 15 tending. to hold the door open, even thoughthe door controlling handle 3| is moved to door closed position, and so long as a passenger is standing upon the treadle switch device I8, thus insuring that the door cannot be closed so long as a-passenger is standing upon the treadle switch device.

With the valve 96 seated and the valve 95 unseated, fluid under pressure also flows from the main reservoir I2 and from the pipe I00, in the manner described, to the piston chamber IE5 of the interlocking piston device I9, whereupon the piston H6 is moved to the right until the stop shoulder I29 engages the bushing I30, and in the event that the operating lever 21 had not been moved to effect a service application of the brakes suflicient to retain the vehicle at rest, for

example upon a grade, the piston IIIi moves into engagement with the rod H9 andforces the operating lever 2| in a clockwise direction sufficient to effect the desirable brake cylinder pressure for retaining the vehicle at rest. So long as fluid under pressure is supplied to the left face of the piston H6, the brake valve device is held in the position to which it has been moved by treadle switch device I3, the spring ISI forces the bridging switch member I I I to its upper and open position, thereby interrupting the circuit through the electro-magnet winding 91 and permitting the spring I06 to force the valve 95 to its seated position and to unseat the valve 98.

With the valve 95 seated and the valve 96 unseated, fluid under pressure within the piston chamber 19 of the door engine device l5 and piston chamber H5 of the interlocking piston device 59 is vented to atmosphere, through passage and pipe I00, chamber I02, past the open valve 96, chamber 94, and atmospheric passage I03. With the fluid under pressure in the valve chamber 19 reduced, the fluid under pressure within the valve chamber 82 and acting on the left face of the piston 8|, moves the piston and slide valve 83 to the right against the action of the spring 35, so that the passage 90 is uncovered by the'slide valve and the passage 89 is connected to the atmosphere through the cavity 88 in the slide valve 83 and the atmospheric passage 9!. With the slide valve in the door closed position shown, the higher fluid pressure acting on the left face of the piston 14 moves the rod lit to the right or to door closed position, thus turning the gear segment 11 in a counterclockwise direction so as to eifect closing movement of the door mechanism.

With the pressure of the fluid in the piston chamber H5 of the interlocking piston device l9 reduced in the manner described, and in the event that the operator has removed his foot from the foot pedal 38 and has moved the operating handle 3! to the door closed position, the spring 22 forces the piston I I6 to the left position shown, through the medium of the operating lever 2| and the rod H9.

As a further precaution against the opening of the door without first eifecting an application of the brakes, the operating shaft 29 is provided with a cam 32, which, when the shaft is turned to effect operation of the valves 54 and 48 for closing the circuit across the contact 66 turns the lever 34 in a counter-clockwise direction and thus effects movement of the operating lever 2| of the brake valve device to application position through the medium of the pin 36 and the valve lever 42.

In the event that the operator has not removed his foot from the foot pedal 38 during the operation of opening and closing the door of the vehicle in the manner above described through operation of the handle 3|, the brakes will be applied until the operators foot is removed from the pedal and the pin 35 is permitted to rise to the release position shown. The spring 22 may then return the operating lever 2| of the brake valve device to release position. The equipment is then in the condition for a subsequent application of the brakes and opening and closing operation of the doors.

It is apparent from the foregoing, that an effective interlocking means is provided for preventing release of the brakes while the vehicle door open and while a passenger is standing upon the treadle switch in front of the door and that the interlocking means assures an application of the brakes with sufiicient force to hold the car at rest on a grade in the event that the operator has not applied the brakes With suflicient force through the medium of the foot pedal when bringing the vehicle to rest to properly'retain it at rest. It is also apparent that proper sequence of operation is assured by means of the apparatus above disclosed.

In addition to that disclosed in the above-mentioned copending application Serial No. 698,242, other safety car equipments, similar to that described herein are disclosed and claimed in the copending application Serial No. 698,243 of David W. Lloyd, filed November 16, 1933 and in my copending application Serial No. 19,378, filed May 2, 1935, both applications being assigned to the assignee of this application.

While but one embodiment of the invention is herein disclosed it is obvious that omissions, additions and other changes may be made in the construction of the control equipment without departing from the spirit of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a fluid pressure brake system, the combination with a brake valve device operable to eifect an application of the brakes, manually operated means for operating said brake valve device, and a door engine device for opening and closing a door and controlled by said manually operated means, of fluid pressure actuated means also controlled by said manually operated means for also effecting operation of said brake valve device for effecting an application of the brakes.

2. In a fluid pressure brake system, the combination with a brake valve device operable to effect an application of the brakes, manually operated means for operating said brake valve device, and a door engine device for opening and closing a door and controlled by said manually operated means, of fluid pressure actuated means also controlled by said manually operated means for also eifecting operation of said brake valve device for effecting an application of the brakes and for preventing release movement of said brake valve device so long as the door engine device is in door-open position.

3. Ina fluid pressure brake system, the combination with a brake valve device operable to effect an application of the brakes, manually operable means for operating said brake valve device, a fluid pressure actuated door engine device, and manually operable means for controlling said door engine device, of power driven means controlled by the last said manually operable means for also actuating said brake valve device.

4. In a fluid pressure brake system, the combination with a brake valve device operable to effect an application of the brakes, manually operable means for operating said brake valve device, a fluid pressure actuated door engine device, and manually operable means for controlling said door engine device, of power driven means for also actuating said brake valve device controlled by the last said manually operable means and the said door engine device and cooperating with said brake valve device to prevent release movement thereof so long as the door engine device is in door-open position.

5. In a fluid pressure brake system, the combination with a brake valve device operable to eifect an application of the brakes, manually operable means for operating said brake valve device, a fluid pressure actuated door engine device, a current responsive valve device for controlling movement of said door engine device, and manually operable switch means for controlling said current responsive valve device, of power driven means controlled by said current responsive valve device for also actuating said brake valve device.

6. In a fluid pressure brake system, the combination with a brake valve device operable to effect an application of the brakes, manually operable means for operating said brake valve device, a fluid pressure actuated door engine device, a current responsive valve device for controlling movement of said door engine device, and manually operable switch means for controlling said current responsive valve device, of power driven means controlled by said current responsive valve device for also actuating said brake valve device and for preventing release movement of said brake valve device so long as said current responsive valve device is in door-open position.

'7. In a fluid pressure brake system, the combination with a brake valve device operable to effect an application of the brakes, manually operable means for operating said brake valve device, and a fluid pressure actuated door engine device, of a current responsive valve device for controlling movement of said door engine device, a manually operable switch device for controlling said current responsive valve device, a power driven means controlled by said current responsive valve device for also actuating said brake valve device, and a switch operable by said for also controlling said current responsive valve device.

8. In a door and the combination with a brake valve device operable to effect an application of the brakes, a door engine for controlling a car door, and fluid pressure operated means for controlling said door engine, of a movable abutment for effecting the operation of said brake valve device to apply the brakes, said abutment being operated by fluid under pressure supplied to said fluid pressure operated means. 7

9. In a fluid pressure brake, the combination with a brake valve device operable to effect an application of the brakes, manually operated means for operating said brake valve device, and a door engine device, of fluid pressure responsive means for also operating said brake valve device to effect an application of the brakes, and current-responsive means controlled by said manually operated means for controlling said door engine device and said fluid pressure responsive means.

10. In a fluid pressure brake, the combination with a brake valve device operable to effect an application of the brakes, manually operated means for operating said brake valve device, and a door engine device, of fluid pressure responsive means for also operating said brake valve device to effect an application of the brakes, and current-responsive means controlled by said manually operated means for simultaneously controlling said door engine device and said fluid pressure responsive means.

11. In a fluid pressure brake, the combination with a brake valve device operable to effect an application of the brakes, and a door engine device, of manually operable means for operating said brake valve device, means mechanically connecting said manually operable means to said brake valve device for transmitting movement of the manually operable means to said brake valve device for operating it to application position, fluid pressure responsive means for also moving said brake valve device to application position, and current-responsive means controlled by said manually operated means for controlling said door engine and said fluid pressure responsive means.

12. In a fluid pressure brake, in combination, a brake controlling valve device operable to effect application and release of the brakes, means automatically actuable from the normal position thereof to effect operation of said valve device to effect an application of the brakes, a door endoor engine device brake controlling apparatus,

gine device, and manually operable means for controlling said door engine automatically actuable means.

13. In a fluid pressure brake, in combination, a brake controlling valve device operable to effect application and release of the brakes, means automatically actuable from the normal position thereof to effect operation of said valve device to effect an application of the brakes, a door engine device, manually operable means, and means controlled by said manually operable means for controlling'said door engine device and said automatically actuable means.

14. In a fluid pressure brake, in combination, a brake controlling valve device operable to effect application and release of the brakes, means automatically actuable from the normal position thereof to effect operation of said valve device to effect an application of the brakes, a door engine device, manually operable means, and means controlled by said manually operable means for simultaneously effecting operation of said door engine device and actuation of said automatically actuable means.

15. In a fluid pressure brake, in combination, a brake controlling valve device operable to effect application and release of the brakes, means automatically actuable to effect operation of said valve device to effect an application of the brakes, a door engine device, and manually operable means adapted to operate said valve device and to control the operation of said door engine device and said automatically actuable means.

16. In a fluid pressure brake, in combination, a brake controlling valve device manually operable to effect application and release of the brakes, a fluid pressure actuated door vice operated to door-open position upon fluid under pressure being supplied thereto, manually operated means adapted to control the supply of fluid under pressure to said door engine device, and means operated by fluid under pressure supplied to said door engine device, adapted to cause automatic operation of said valve device to effect an application of the brakes.

17. In a fluid pressure brake, in combination, a brake controlling valve device operable to eiiect application and release of the brakes, means automatically actuable to operate said valve device to effect an application of the brakes, a door engine device, manually operable means for effecting operation of said valve device only, and manually operable means for effecting operation of said valve device and said door engine device, and also actuation of said automatically actuable means.

18. In a fluid pressure brake, in combination, a brake controlling valve device operable to eflect application and release of the brakes, manually operated means for operating said valve device, a fluid pressure actuated door engine device operated to door-open position upon fluid under pressure being supplied thereto, said manually operated means being adapted to control the supply of fluid under pressure to said door engine device, and means for preventing operation of said valve device, by said manually operated means, to effect release of the brakes as long as said door engine device is in door-open position, said last means including fluid pressure actuated means operated by fluid under pressure supplied to said door engine device for holding said valve device in brake application position, and means controlled by said door engine device effective to cause the supply of fluid under pressure to said device and said door engine device and to said fluid pressure actuated means to be maintained even though the said manually operated means is operated to brake release position.

19. In a fluid pressure brake, in combination, a brake controlling valve device operable to effect application and release of the brakes, manually cluding means operated by fluid under pressure supplied to said door engine device for holding said brake valve device in brake application position, and means controlled by said door engine device for maintaining said current-responsive device energized notwithstanding the operation of the manually operated means to brake release position.

20. In a fluid pressure brake for a vehicle, in combination, a brake controlling valve device operative manually to effect application and release of the brakes, a door engine device operative upon fluid under pressure being supplied thereto to cause opening of a vehicle door and upon fluid under pressure being released therefrom to cause closing of the door, and means cooperating with said valve device and subject to the pressure of the fluid supplied to operate the door engine device to cause opening of the door, for preventing the operation of the said valve device to effect release of the brakes.

21. In a fluid pressure brake for a vehicle, in combination, a brake controlling valve device 0perative manually to effect application and release of the brakes, a door engine device operative upon fluid under pressure being supplied thereto't'o cause opening of a vehicle'door and upon 'fluid' under pressure being released therefrom to cause closing of the door, valve means for controlling the supply of fluid under pressure to and the release of fluid under pressure from the door engine device, and a movable abutment subject to device. I

22. In a fluid pressure brake for a vehicle, in combination, a brake cylinder, a self-lapping valve device having an operating element normally in a brake release position, said valve device be-- ing operative to cause fluid under pressure to be supplied to and released from the brake cylinder to effect application and release of the brakes, the degree of the brake cylinder pressure being in accordance with the degree of displacement of the operating element out of the normal brake release position, manually operative means for moving the operating element, a door engine device operative upon fluid under pressure being supplied thereto to cause opening of a vehicle door and operative upon the release of fluid under pressure therefrom to cause closing of the door, a movable abutment connected to and movable with the said operating element,

said abutment being subject to the pressure of the fluid supplied to the door engine device and effective to prevent reurn of the operating element toward its normal brake release position aslong as the supply of fluid under pressure to the door engine device is maintained.

ELLIS E. HEWITT. 

